The present invention relates to a hand tool for pulling and stringing wire, rope or cable through building walls, ceilings, pipes and conduits, by use of a one way ratcheting die.
Electricians are routinely required to pull wires through lengthy conduits or pipes. It is not uncommon for such conduits to stretch many feet in length and contain a number of elbows and turns which increase the difficulty of pulling wires through the conduits.
The typical technique for pulling wires through a conduit entails initially pushing a length of resilient spring steel fish tape through the conduit. The fish tape has a substantially rectangular cross section which, in combination with its spring steel construction, allows it to bend around corners within the conduit while maintaining sufficient rigidity to be pushed a considerable distance. A flexible leader with a rounded tip is attached to a free end of the fish tape. The leader enhances the ability to negotiate corners as the fish tape is pushed through the conduit. After the leader reaches the terminal end of the conduit, the electrical wires are attached to the leader. The fish tape and attached wires are then pulled back through the conduit until the leader and the end of the electrical wires exit the end of the conduit into which the leader was initially pushed.
When pulling the wire, one person pulls the fish tape from the one end of the conduit while a second person feeds the electrical wire into the other end of the conduit. The fish tape and the wires are pushed and pulled in increments or strokes of several feet at a time. The two people at opposite ends of the conduit develop a rhythm which allows them to pull and feed wire at the same time, and this rhythm enhances the speed and ease by which the wire is pulled.
Existing pipe pulling devices, such as U.S. Pat. No. 996,259 issued to Kern, are limited to large diameter rigid materials such as pipe, and do not allow the pulled material to be easily travel through the device once the pressure is released. Such conventional devices utilizes a hand tightening screw to allow the device to engage with the pipe and do not automatically adjust with changes in pipe diameter. For example, the Kern device does not automatically adjust to change in pipe diameter and therefore instantly releases a smaller diameter pipe until a hand screw is adjusted by a user to provide pressure on the smaller diameter pipe.
Although the fish tape/cable is sometimes guided by hand, it is difficult to adequately grip the tape when pushing long distances or when pulling a large number of electrical wires, due to the heavy force required to maneuver the tape and the attached wires through the conduit. To gain additional force, a hand tool such as a pair of pliers is typically used to grip the cable. Pliers are frequently used due to the ready availability of pliers within the electrician's tool belt or toolbox.
However, pliers are inconvenient and inefficient for lengthy wire pulls due to the large number of individual pulling strokes required. With each stroke, the electrician must release the jaws of the pliers from the tape and then firmly re-grip the tape at a point several feet further away. Time is lost in releasing and firmly resetting the pliers for each pulling stroke of the fish tape. Furthermore, it is often difficult to maintain the pushing and pulling rhythm or the rhythm proceeds at a slow pace, when pliers are used.
Furthermore, electricians typically pull the cable with only the one hand which holds the pliers. Consequently, some electricians develop back problems due to repeatedly pulling the heavily loaded cable with one hand, because of the detrimental erogomic position in which pulling occurs. Also, Pliers come with a risk of the cable slipping through it any time.
Although pliers are the predominant hand tool used for pulling electrical wire, other tools have been developed for the sole purpose of gripping or pulling fish tape. However, these tools suffer from one or more disadvantages which have precluded their widespread acceptance by electricians.